haplm's XV-01 carbon mod

[bvrc]

Originally Posted by haplm

End time is precisely measured by an IR/laser gate, and transferred into a timing software.

The whole thing is running on some arduino box (HW), and some guys wrote the SW (I believe there's more than one system, but I'm not sure).

If you need to know more about some part of this, let me know, I will ask. I'm just talking to one of the guys operating this, because I'm asking him for source data from the timing system, so I can analyze them (turns out it is bunch of XMLs).

I'm definitely interested in more info! Keep us posted on what you learn.

[haplm]

Originally Posted by bvrc

I'm definitely interested in more info! Keep us posted on what you learn.

I believe that what they were using during my last race is close to perfect. The software is called RZXtreme (RZ stands for "stage" in czech). It can be deployed to couple of computers, where one of them controls the race, the other one shows start screen for racers (so you know who's starting next, who after him, etc.), and it also provides web server where people can see online results. There you can see list of drivers, position on the start, start time, results for different categories, etc. Example here.

Unfortunately the web is in czech only, but try to turn auto-translate in Google Chrome. Reading their web, it seems that there's a module allowing translation to other languages, so there already might be an english version (of the software).

The software seems to be freely downloadable (you just need to build gate capturing finish time). PM me if you need some help around this.

[haplm]

First - new tires

(VR Pins medium compound and VR Rally Blocks soft compound):



Next - race update:

Yesterday's race was a combination of tarmac, gravel and turf. I've been comparing modified Fastrax Rally Blocks (softer Tamiya Rally Blocks), VR Tyres Pins (medium and soft compound), VR Tires Rally Blocks, and HPI Rally tires.

There were 10 stages, doing changes on the car is allowed after every second stage. So I couldn't come back and retest tire that I have already ran.

In first two stages, I have suffered from rocks getting into my steering, until I have fixed that problem using duck tape like this:



Basically the problem was, that with full steering angle, the wheels are shooting rocks directly at the steering assembly. And there is some space on the diff box where rocks can get stuck between it and the carbon steering extension. So the goal was to remove this space, and make it hard for rocks to settle. Seems like it worked.

Another problem was, that the rocks not only got into the steering, they have also entered the belt are through the unprotected front pulley area. I have almost destroyed the front pulley (will have to replace it), and the belt as well. So another piece of duct tape solved that problem as well:



Since I was running HPI tires first, I have no credible data for them. However, they felt OK on gravel and turf, not so much on tarmac (probably too hard compound).

VR pins (both compounds) have excellent traction on turf. In fact they have so much traction that it is very easy to roll the car because of that. Both compounds also perform well on gravel. Medium compound is not really great on tarmac, soft is OK (but wearing quickly).

VR Rally Blocks - although soft compound, they didn't felt right on tarmac. Good on gravel, OK on turf. I wanted to write them off, unless I found out that I've recorded my best stage time on them.

Modified Fastrax Rally Blocks - the tire is quite soft, providing very good traction on tarmac, good on gravel, OK on turf. However, I have recorded slower stage times on them (not sure why, it could have been the driver :-)).

Resolution is, that unsurprisingly pins are good for turf/gravel, modified Fastrax rally blocks for tarmac/gravel, HPI rally for gravel/turf, VR Rally Blocks tarmac/gravel (but choose soft or ultra-soft compound).

Speaking of Modified Fastrax Rally Block - I did this to it (it makes the tire really soft):



During the race, I have learned that this is an outdated thing, suppressed by this modification:



To do this, you need scissors, pliers, and couple hours of time...

My race gallery (my car obviously missing):
https://goo.gl/photos/uKE3ZWEFgNRhgt1g8

[haplm]

I haven't update the thread for a while, so here are the latest updates:

Shocks
I have managed to obtain (and build) Team Associated Big Bore (12mm) shocks, together with plethora of Team Durango and Team Associated springs. I did this mainly because I was convinced that there's no good selection of springs for my 75mm Gmade shocks.

To my surprise, I have found out (of course after spending all the money on new set of shocks), that the springs that fit 12mm Big Bore shocks (TA, Team Durango, Kyosho, etc.) are in fact compatible with Gmade. So now I have two sets of shocks, which can accept all the springs I have.

The problem with Gmade is, that I have originally bought XD variant, and I've already blown 2 diaphragms after just couple of races. This was most likely because I've been using them without bump stops. However, using bump stops really really limits the shock travel, rendering them almost unusable for this application. Therefore I have switched to Aeration caps, which solve the diaphragm problem (the shock is just a bit harder to build). However, even with the aeration cap, the shock seems to have few millimeters shorter travel than TA shock with 23mm body and 21mm shaft.

Because of that, and because the TA shocks are better build quality than Gmade, I will stick with TA for next season.

Ride Height
Since I now have shocks where I can easily modify their length, I've decided to modify the chassis to achieve 25-30mm ride height.

Because I'm working on a new chassis, I could potentially destroy the current one, so I took my Proxxon mill, and was milling pretty much the whole day.

The result is impressive. I have achieved 28mm rear and 26mm front. However, this required not only milling lower plate under the a-arms and where steering mount extension hits the plate, but also top plate (to unbind steering links when shocks are compressed), and finally front a-arms and c-hub. Basically everything, as at this height, there was binding simply pretty much everywhere.

With this ride height, 75mm shocks no longer work on the rear for most of the mounting positions. So I have shortened 27.5 Body / 27.5 Shaft shocks (originally 85mm) to ±80mm, and used them in the rear. 23B/21S shock (75mm) is OK int he front, mostly thanks to only possible mounting position (the most vertical one).

Springs
The real soft springs can be bought from Team Durango (1.89, 2.44), followed by soft TA springs (2.85, 3, 3.15), medium TA, hard TA. With this selection, balanced natural frequency can be achieved even when there's so much difference in weight distribution front/rear.

Next Steps
I believe I have a final version of v2 of the carbon plates, with following changes:

• Ride height increased to 25 - 30mm range
• Shorty LiPo can be positioned alongside the rear axle on the bottom plate
• ESC and light controller can be mounted on the bottom plate
• Hole for fan and hole for cables on the upper plate

I also need to change the mounting of servo and steering a bit, as the extreme movement of a-arms with the desired ride height requires that.

Next Body
Is Tamiya Datsun 240z Rally, custom paint scheme, with light buckets and Killerbody light controller. However, the KB controller is not really a good one. It flashes rear light during braking, and it is dimly lit even during going forward. So I have ordered OB1 v3.1 controller, which should have much better programming.

[haplm]

Patrik (CiruS.cz) finally had time to cut my new plates, and here they are:


Let's see how they work in real life... The plates are accompanied by 85mm damper mounts, front is on the picture, rear is already mounted on the current car.

I've also got the OB1 light controllers (v3.1, but 3.0 might be better choice for certain bodies), which work much better than Killerbody (real reversing light for example), and they have much much broader configurability. This is THE controller to get, if you want to use LEDs, IMO.

[haplm]

The car is slowly taking shape:




3mm of spacers to get some pro-dive (kickup) and increased caster:


Unfortunately I'm stalled until I get Kyosho P5 o-rings and Tamiya Aluminum Differential Unit Cover, as I want to use really light oil in diffs (2k and 3k), which neither standard, not TRF o-rings will hold inside.

[haplm]

The build is going well. I've got the ESC (Sanwa Super Vortex Generation 2) and servo (Spektrum Low Profile HV Digital Race Servo S6270), so after couple days of soldering, this is what I've got.

Separate power wires for ESC and the HV Servo + Fan:


Servo/fan power connectors:


The whole car as of now:

[haplm]

Christmas gave me enough time to finish all the electronics, mount suspension, and even create most of the dirt cover:


Both the ESC and the receiver are (will be) completely sealed off from the environment. Receiver is an easy job, as it is not going to overheat. That can't be said about the ESC, so the WTF fan on the top plate is connected straight to the 2S Lipo battery, making an incredible airflow, although it is the smallest one available (25mm), as anything bigger won't fit my top plate:


ESC cover, right (and not so interesting) side:


Left side with air intake and mounted ESC switch:


I still need to put some filter on the air intake holes, so the dust doesn't get in, and mount light controller. Since I'm running the ESC in SSL mode, AUX1/CH3 is used for changing the ESC parameters. So I can only use one channel to control the lights (CH4). Moreover, because of the Sanwa's SSL protocol being used between the ESC and receiver, the light controller can't really read the throttle position (and I don't care about left/right signals). So the only thing that I'm going to be able to do with lights is to turn them off and on, but I guess that's OK on a rally car...

Speaking of ESC and SSL, I really love the possibility of changing most of the ESC parameters from my transmitter, on the fly. This is making the whole process so much easier, and in fact usable. Previously I have just tried to find a good enough setup, and never go through it again. Here, I can adjust stuff using dials on transmitter as I drive the car. So convenient...

[haplm]

So, the car is pretty much done:


Electronics is sealed against water, and hopefully dust too. If I'm lucky, I may not need to start the fan that is pumping air through the ESC box at all, because during my tests at home, I have never pushed the ESC further than 40deg C. If the temperature rises, the fan will suck the air out of the ESC box (so water doesn't get in through it). I've placed a fuel filter (with some filter oil) over the intake holes, which I hope will catch most of the dust and debris:


Last thing that I've had to do is a camber mount adjustment on the hub side. Since the carbon chassis doesn't use the original plastic part, which puts camber link mounts quite low on the chassis side, I had to put them higher on the hub side (to get a reasonably high roll center in the rear):


I admit that it doesn't look nice, but it works. To check it a "scientifically", I have started measuring all the aspects of the car and creating RC Crew Chief model. This is what is says about Gravity and Roll Centers:


What I don't like is, that my rear RC is slightly lower than front. So after couple of races, I plan to raise it even higher by shimming the rear a-arm mounts, and see how it will affect the handling.

[BOONER]

I really love what you have done with your build! Looks like a lot of fun. I was just wondering if you could confirm the size of your TA big bore shocks? Are you using the same size for front and rear?

[haplm]

Originally Posted by BOONER

I really love what you have done with your build! Looks like a lot of fun. I was just wondering if you could confirm the size of your TA big bore shocks? Are you using the same size for front and rear?

It is a lot of learning :-). Right now, I'm trying to create 3D scan of some of the original parts, modify them, and print them on 3D printer :-).

Anyway, TA shocks. No, they are not the same size. With my ride height, 75mm shocks no longer work on the rear for most of the mounting positions. So I have shortened 27.5 Body / 27.5 Shaft shocks (originally 85mm) to ±80mm, and used them in the rear. 23B/21S shock (75mm) is OK int he front, mostly thanks to only possible mounting position (the most vertical one). The longer shocks in the rear are supported by a custom carbon shock mount. I also have one for the front shocks (so I could switch to the same 85mm shocks all around), but I don't want to use it as it would push the body way too up. Maybe later :-).

Since I have updated the rear camber mount (see one of my previous posts), I'm suffering from the rear drive shafts not being long enough for some shock mounting positions for ride height over 28mm. I would need something like 40mm shaft instead of standard 39mm. It doesn't seem that Tamiya is making one, so I'm trying to find some 3rd party one. For now, I'm simply staying within 28mm ride height, I guess it is enough anyway...

[BOONER]

Thanks for you help. I have purchased the long damper mod and I have been trying to find the best option dampers for my car and I think I have finally decided on the TA big bore shocks. Now I just have to buy them!!

[haplm]

Originally Posted by BOONER

Thanks for you help. I have purchased the long damper mod and I have been trying to find the best option dampers for my car and I think I have finally decided on the TA big bore shocks. Now I just have to buy them!!

Just make sure that you don't make the same mistake as I did, and don't buy Big Bore v1. There're v2 also available, and to confuse it even more, you can also get V2 FOX Shocks with Genuine Kashima Coat.

I haven't bought v2 because I thought these are v2 small bores, which Big Bores v1 replaced. BB v1 are leaking a bit, which was solved with BB v2.

All the BB components are listed here (https://www.teamassociated.com/parts...rts/big_bores/).

[haplm]

Originally Posted by haplm

Just make sure that you don't make the same mistake as I did, and don't buy Big Bore v1. There're v2 also available, and to confuse it even more, you can also get V2 FOX Shocks with Genuine Kashima Coat.

I haven't bought v2 because I thought these are v2 small bores, which Big Bores v1 replaced. BB v1 are leaking a bit, which was solved with BB v2.

All the BB components are listed here (https://www.teamassociated.com/parts...rts/big_bores/).

But truth is, that when I was searching for a new pair of shocks yesterday (I need one more 85mm pair), I have ended up buying v1 again. v2 is mostly out of stock, and there's not so good selection of tapered pistons. I guess I can live with small leakage (up to 4 drops per race day).

[haplm]

Something is brewing.... Well, printing....

[4roller]

Originally Posted by haplm

Something is brewing.... Well, printing....

Ooooh adjustable! What material are you using to print? I should jump on the 3d printing, seems like custom parts for pretty cheap. The idea that you can basically prototype anything you think of, really fits the hobby.

[haplm]

Originally Posted by 4roller

Ooooh adjustable! What material are you using to print? I should jump on the 3d printing, seems like custom parts for pretty cheap. The idea that you can basically prototype anything you think of, really fits the hobby.

Right now, I'm using simple PLA, because I'm still prototyping, and this is what my colleague's Prusa i3 Mk2 printer is setup to print with.

But later on, I will use either ColorFabb's XT-CF20, or CarbonX Carbon Fiber Reinforced Nylon 3D Filament for the final prototype, which will go to the car and into the race. If that works, I will send it to a guy who can print with industry grade nylon with either carbon fibre or kevlar (that unfortunately still requires something like $20k printer). That should be as strong as aluminum.

I actually have high hopes for this, because this way, I can create pretty much what I want/need. So exactly as you say - 3D printing should be really great for the hobby...

Besides the rear camber link, I also want to design front camber links, and dust cover(s). Which means, that most of my XV will be in fact custom :-).

[mudbeast2]

That is a awesome build! I just ordered XV-01 & can't wait to build. Where did you get the Toyota body with the light buckets? Or can I use 180mm or 200 mm bodies?

[haplm]

Originally Posted by mudbeast2

That is a awesome build! I just ordered XV-01 & can't wait to build. Where did you get the Toyota body with the light buckets? Or can I use 180mm or 200 mm bodies?

You can get the light buckets from Killer Body's GT 86. They fit perfectly, and can be ordered separately from the body.

[haplm]

And here we go...